Process of ore flotation



' Patented Nov. 24, '1931',

j -UNITED STATES PATENT O I IRA E. DERBY AND cam 13. CUNNINGHAM, orINDIANAPOLIS, INDIANA, As'sIeNons no PETER c, REILLY, or INDIANAPOLIS,INDIANA rnocnss or ozan ILorA'no'N No Drawing.

The present invention relates to the froth flotation of ores, othermetalliferous materials, by the useof certain classes oftri-thiocarbonate compounds as hereinafter discussed, The invention isbased on the use of the mono-ester acids or their alkali oralkalineearth metal salts. Thus the salts of mono-ethyl tri-thiocarbonic acid(or of other mono-alkyl or mono-aryl tri-thiocarbonic acids) or theacids themselves constitute excellent collecting agents for use inflotation. These compounds can be prepared, for example, by reaction ofmercaptans, carbon bisulfide, and caustic alkali or sodium sulfidex Wegive the following Classification of the tri-thiocarbonate type ofcompounds WhlCh can be conveniently employed in flotation in accordancewith the present invention: (a)

the acid esters of tri-thiocarbonic acid, including the alkyl .and thearyl derivatives such as, for example, the mono-ethyl ester, themono-propyl ester and the mono-phenyl derivative (b) the metallic saltsof the mono? ester acids of tri-thiocarbo'nic acid such as, for example,the sodium, potassium or barium salts of mono-ethyl tri-thiocarbonicacid;

(a the ammonium salts of the mono-ester aclds of tri-thiocarbonic acidsuch as, for example, ammonium ethyl tri-thiocarbonate; (d) the salts ofthe mono-ester acids of trithiocarbonic acid formed with nitrogenousbases, such as, for example, the mono ethyl' tri-thiocarbonate salts ofhydroxylamine or (In these salts the nitrogenous ase, which is asubstituted ammonia, may be considered as functioning somewhat like ametal in the compound, the reaction bein analogous to the reaction ofammonia witfi an acid to form ammonium salts;)

The substances above "referred to come within the generic formula KsM'in which B may represent an alkyl or aryl radical, and M may representan inorganic radical (such as the ammonium radical), alkali or alkalineearth metal, hydrogen, or substituted ammonium complex (for example thatobtained by the reaction of a nitrogenous including sulfid ores, and

Application filed March 19, 1926. Serial No. 96,062,

base with a tri-thiocarboni'c acid compound. The characters M and R areused in this sense hereinafter,

In order to make ourselves entirely clear,

We will state that the tri-thiocarbonic acid is a well known substancehaving the formula CS (SH) Ethyl tri-thiocarbonic acid (which can becalled hydrogen mono-ethyl tri-thiocarbonate), is likewise a well knownsubstance, having the formula SC H CS-= SH. \Vhile these substances aremore or less well known, having been described in text books ofchemistry for many years, they do not seem to have heretofore beenemployed or suggested for employment in the art of mineral flotation.According to our researches, these substances are active flotationagents, and the salts of the a1kyl-tri-thiocar; bonic' acids are foundto be especially active: An illustrative example would be C H S- 'CS---SK. While these substances have great selective action or collectingpower for sulfid minerals, in the flotation operation, they do not haveany substantial frothing properties, so that an appropriate frothingagent such as pine oil should be employed iniconjuncti'on therewith, incarryingout the froth flotation operation.- In carrying out theflotation operation it is preferable to use either a neutral or alkalinecircuit depending on the character of the ore. In an acid circuit thesalts of the acid ester tri-thiocarbonate compounds are unstable, thedegree of instability depending 'on the acidity of the circuit and ontheparticular compound used. ,A sli htly acid circuit can besuccessfully use however, if suificient reagent is added to take care ofthe loss due to decomposition duringthe flotattion operation, forexample, an acidity of fifteen hundredths per cent (0.15%) of sulfuricacid was successfully used with sodium ethyl tri-thiocarbonate on acopper sulfide ore by doubling the amount of reagent employedwith thesame ere in a lime circuit.

As a specific example of the process,.tov

which the invention of the present case 1s not restricted, the followingisgiven An ore containing copper-sulfid wasmade into a pul withwater,and an amount of sodium et yl tri-thiocarbonate was added equivalent toone-tenth of a pound (0.1 lb.) of this material to a ton of the dry ore.An amount of pine oil was then added, .as a frothing agent, equivalentto .22 lb; per ton of ore, and 4 lbs. of hydrated lime was added and themiXture'was then subjected to aeration flotation, in a Janney machine ofthe ordinary construction.- We were able in this manner to separate ahigh grade concentrate, and-to leave a tailing containing practically nocop-per.

The quantity of tri-thiocarbonate compound to be used in the flotationoperation may be varied, depending upon the specific ore under treatmentandother'factors. -We find that from five hundredths (0.05 lb.) pound totwo pounds (2 lbs.) or more of trithiocarbonate compound per ton of dryore can be used successfully in floating ores of this character.

It will be understood that the tri-thiocarbonate compound can be used asthe sole or essential selecting or collecting agent, or it can be usedin conjunction with various oily materials, such as are shown in the artfor this purpose. The tri-thiocarbonate compound, either alone or withother flotation.

agents can be incorporated with the ore while the same is beingwet-ground, for example in a tube mill. In other modifications, the orecan be ground Without the addition of the tri-thiocarbonate or oilyflotation or frothing agents,'and these can subsequently be dissolved oremulsified and-added to the water with which'the pulp is to be formed,or the tri-thiocarbonate can be added to the pulp of ore and water anddissolved or emulsified therewith. The order of adding the ore, waterand flotation agent and frothin agent, accordingly can be varied to suitthe particular ore under treatment orto suit the conditions of the plantin which the operation is to be conducted.

What is claimed is:

1. A process which comprises subjecting me-talliferous material to'afroth flotation treatment while. associated with a tri-thioin which Mrepresents hydrogen or a metal carbonate substance containing onehydrocarbon radical only replacing a hydrogen ,atom of thetri-thiocarbonic acid.

2. Froth flotation of material in the pres- "ence of an agent includinga tri-thiocarbonate of the type Sulphalkyl o M or an inorganic radicalacting as a metal or a substituted ammonium complex.

3. The step of froth flotation of material in the presence of an agentincluding a trithiocarbonate of the type l SCzHs s=o I in which Mrepresents'a hydrogen or a metal or an inorganic radical acting as ametal or a substituted ammonium complex.

4. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of an alkali metal salt of monoethyltri-thiocarbonic acid.

. 5. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of a derivative of tri-thiocarbonatehaving the following structural formula:

in which R is an alkyl or aryl group and M is an alkali metal.

'6. In the art of concentrating ores, the

herein described step which comprises subjecting the ore to froth'flotation in the presence of a compound containing the radicalconsisting of me'tals, hydrogen, and radicals functioning. as a metal.

8. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the material to be concentrated in theform of a pulp to a froth flotation operation in the presence of anorganic-inorganic derivative of tri-thiocarbonic acid having thestructural formula:

in which R is an 'alkyl or aryl group and M represents hydrogen or ametal-or an inorganic radical acting as a metal or a substi- 1 tutedammonium complex.

9. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of an organic-inorganic derivativeof tri-thiocarbonic acid having the following structural formula:

where R represents a hydrocarbon radical and M represents metal,hydrogen, or a radical functioning like a metal.

'10. In the process of concentrating ores and mmerals by flotation, thestep which comprises subjectin ithe same in' the form of a pulp to afrot flotation operation in the presence of a derivative oftri-thiocarbonic acid having the following structural forin which R isan 'alkyl or varyl group and M is a metal hydrogen or aninorganicradical 11. In the 'process of concentrating ores and mineralsby flotation, the step which comprises subjectin the ore in the form ofa pulp to a froth otation operation in the presence of an alkali. metalsalt of monoethyl tri-thiocarbonic acid.

12. A process of flotation in the presence of an agent including atri-thiocarbonate of the type in which M represents hydrogen or a metalor an inorganic radical acting as a metal or a a substituted ammoniumcomplex.

25 13. In the process of concentrating ores and minerals by flotation,the step, which comprises subjectin the same in the form of a pulp to afroth otation operation in the presence of a nitrogenous base salt of amono- Y 30 ester of a tri-thiocarbonic acid.

14. In the process of concentrating ores \and minerals by flotation, thestep,- which comprises subjecting the same in the form of pulp to afroth flotation operation in the presence of a pyridine base saltof amono 35 ester'of tri-thiocarbonic acid'..-

In testimony whereof we have signed our names to this specification. 1 r1 IRA'H. DERBY. ORIN D. CUNNINGHAM.

